When I become an evil superpower, I need to remember to breed lots of goblins and trolls to do my hard labor and dirty work. They seem to ask little satisfaction other than gratuitous violence and gore, and as for feeding them, well, all indications are that they eat each other, so they'd be fairly easy to maintain.
On the minus side, they are volatile and appetite-driven, and tend to turn on one another with little or no provocation. Labor relations will be key. But they're none-too-bright, so keeping them somewhat motivated should be a cinch (further note to self: collect tips on crowd-pleasing yet non-commital rhetoric from liberal Democrats), and, in-fighting aside, they do not generally question or rebel against their superiors to whom they own allegiance.
When outsourcing even to India becomes prohibitively expensive, outsourcing to Mordor could be our next alternative.